Multistage turbine



K Sheets-Sheet 2 Feb. 7, 1933. o. D. H. BENTLEY MULTISTAGE TURBINE FiledMaron 5, 1930 Feb- 7, 1933- o. D. H. BENTLEY 1,896,809

MULT I STAGE TURBINE Filed MaICh 3, 1930 3 Sheets-Sheet 3 Patented Feb.7, 1933 W- UNITED :STATES PATENTQFFICE;

OLIVER D. H. BENTLEY, or NORFOLK,` MAssACiiUsETTsQAjssrGivoR To. n. F.STURTEVANT j COMPANY, or HYDE rARK, MASSACHUSETTS, A CORPORATION vor*MASsiioHUsiizTTs MULTTSTAGE 4Tnaiainn j Application led March 3,

Y The present invention relates to m'ultistage turbines.

The principalobject'of thepresent invenltion is to provide a multi-stageturbine of -5 high eiiciency and oi readily manufactured construction.

l With this and other objects in View, as will hereinafter appear, thepresent invention contemplates the provision `of a turbine having aplurality of rotors or wheelswith means for admitting the steam or otherelastic Working iuid to the several rotors in succession according tothe radial fiow principle. The radial low construction is common forsingle f vstage turbines, but for multi-stage turbines, the so-calledaxial flow principle is ordinarily employed. The radial flowconstruction, according to the present invention, is to be preferred notonly because of s'uch manufacturing advantages as simplicity,compactness, and ease of assembly, but also because of the greaterutilization of the energy of the fluid. In the accompanying drawings,Fig. 1 is a longitudinal `sectional elevation of the pre- '25 ferredform of turbine; Fig. 2 is a section on line 2 2 of Fig. 1; and Fig. 3is a section on line 3;-3 of Fig. 1.

The illustrated embodiment of the' invention comprises a turbine havingacasing provided with an inlet 'steam chest 6. The casing is suitablylagged with heat insulating material 8. The shaft l0 is of usual formand is secured to a series of rotors 12 by keys 13. Each rotor hasperipheral or radial flow l i? buckets 14. The buckets of the severalrotors are of increasing size from the inlet to the exhaust end ot theturbine to accommodate the increasing volume of steam. rlhe last stageexhausts into an outlet chamber 15 -43 which is closed by a conical endpiece 16 bolted to the casing. The usual glands or stuiiingboxes 18 areprovided to prevent leakage along the sha-it. i

Fre-m the steam chest 6 the steam is admitted to the irst rotor throughan annular passage 20. The steam from this rotor is eX- hausted radiallyinto an annular inter-stage iiuid directing passage 21 from which it isadmitted according to the radial flow principle to the next succeedingrotor. Other simi- Vby the rings 26 is a diaphragm or separating 1930.'`Serial gNo. 432,637.

lar annular inter-stage `Huid directing :passages 21 receive the exhauststeam from one rotor and-deliver itv toV the next in succession, untilit is `finally*dischargedfrom the last P rotor into the .exhaust oroutlet chamber 15.

OneofV thesepassages 21, namely," the passage be'ween the third andfourth rotors, is indicated at 22 in Fig. 2. lAll of the interstagepassages are of similar form but are of increasing sizeV toward theexhaust end of` the turbine in order to accommodate the increasedvolu'me of steam as 4the pressure decreases. The annular inter-stagepassages are formed in thejstjator of the turbine inthe P followingmannerf Adjacent to the steamA chest 6 Va ring 24is vfitted vintothecasing "sur-` rounding Vand vclose to' thel rst rotor; A series ofclosely-fitted adjoining rings26 is received in the casing. Each ringhas aninternal annular Vmachined groove 28 of general toroidalcontourforming the outer boundary of eachinter-stage passage.V f -Eachring has an inwardly 'extending flange yportion 30.v Extending into eachannular chamber" formed plate 32 vhaving an-outer -to-roidal surfacedefining' the inner bo'unding surface of Aeach inter-stage passagefEachdiaphragm is secured to and spaced from the next preceding ring 26by means 'of a plurality of bolts 34 80 and spacing washers 36, only oneoi which is shown in Fig.f1. j"

As shownin Figs. 2 and, each ring 26 and each diaphragm32, as well "asthe ring 2li4 `and the. casing, are constructed in two parts ysecured bybolting flanges 38 to facilitate assembly. The turbineV may bedisassembled by removing the end cap 16 and separating the casing, afterwhich the entire upper half of the stator, includingthe halfrings andhalf-diaphragms may be lifted off. Thel rings are tightly'securedagainst end- Wise' play by la plurality of pressure bolt as`- semblies,one of which isshown at 41secured in the outer Vend of the casing'andbearing against the outermost ring. l' i At the'center of each diaphragmis secured a serrated plate which engages and'wears into a soft metalbearing 425cm the'shaft to preventleakage of fluid along the shaft.` V100 The several steam admission passages including the initial passage20 and the entrance sides ofthe inter-stage passages 21, are yprovidedwith vanes to directthesteam into the buckets along nearly tangentiallines. For the inter-stage passages,these vanes, whichY areiindicated at44, are' milled or cut 4out of the outer faces of the diaphragms 32,

Each vane is therefore integral with the diaphragm and projectsoutwardlyy therefrom to engage closely with the'next adjacent of therings 26. As shown in Fig.j2, adjacent vanes have parallel fluiddirecting surfaces,

and thus the vanes are Vnecessarily of taperedk form, being of lessthickness attheir inner than at ytheir outer ends." The straightparallel sides'of the lvanes are of considerable length, lat least asgreat as' the perpendicular distance betweenadjacent vvanes, toy form afluid directing throat. lEach vane is roundved at-its outer end 46 topermit non-turbulent entrance of VHuid .into the throat.`

The ring 24 on the inlet 'side (that is, the left side, as viewed inFigl), is similarly vformed with vanes extending intothev passage 20.

Thevanes44, acting'to direct-the fluid toy the rotor in a nearlytangential direction, form nozzles -which nozzles, however, are notnecessarily of the expanding type. Straight sided nozzles, as showninthe drawings, may be used whenthe steam in any nozzle does not expand.to f such' extent that' the pressure is less than"58% of the pressure`at the inlet of the nozzle. 1 Ina six-stage turbine, the pressure dropin any stage will not ordinarily be vgreatenoughjto require expandingnozzles.

Thus, in the illustrated embodiment of the invention,-jif the steamexpands to 58% pressure in each stage, the exhaust steam-pressure islessthan 4%-,ofthe initial pressure.V Ordinarily, this represents afgreaterv expansion than can be .takenfcare of ingasingle turbine, but iffurther .expansion is necessary, lit may be effected by 'theuse ofadditional'stages,

or VbyV cutting the v anes 44 in expanding form.

It will be seen that the invention provides f for radialA flow inV eachstage of a multi-stage turbine. It will be understood that thete'rmradial flow as employed lherein`,is' as usually employed in this art, tosignify a radial component.- ofA flow and to `distinguish from axialIflow` by the total absence of any'axial f or longitudinal component.-lThe radial Aflow e. principle'permits theextraction of a greaterproportion'of useful energy from the'steam in anysingle lstage becauseof the fact that the fluid, in entering and leaving the buckets,

directing vanes in the inter-stage passages.

2. A multi-stage, elastic'fluid turbine comprising a shaft, a pluralityof rotors each provided with a series of peripherally dis-V posedybuckets, andmeans forming radial Howinter-stage passages betweenvadjacent rotors, said-means comprising a diaphragm separating therotorsy and a ring surrounding the diaphragm and having an annularinternal groove spaced from the outer surface of the diaphragm, andiiuid directing vanes formed on the diaphragm and projecting into theinter-stage passages. c.

3. A multi-stage, elastic fluid turbine comprising a shaft, a pluralityof rotors each Yprovided with a series of peripherally disposed buckets,andv means forming yradial flow inter-stagepassages between adjacentrotors, said means comprising a diaphragm separating the rotors and aring surrounding the diaphragm and having an annular interf i nal groovespaced from the outersurface of the diaphragm, each diaphragm and ringbeing split, and bearing means between. the diaphragm and the shaft.

`4. A multi-stage, elastic fluid turbine comprisingfa shaft, a pluralityof rotors along the shaft, each rotor having lsymmetrical peripherallydisposed 'action buckets U- shaped in axial section, astator having anynular interstage chambers between adj acent rotors, each chamber beingU-shaped in axial ing U-shaped portions extending beyond the rotors andwithin the chambers to form continuous U-shapedvinterstage passages.

, VIn testimony whereof I have signed myy name to this specification.V

'OLIVER D. H. BENTLEY.-

" turns completely through an angle of Having vthus ,described theinvention, what is claimed'is: l Y 1.l .A multi-stage, 'elastic fluidturbine comprising a shaft, a plurality of rotors each provided: withaseries-of peripherally disposed"` buckets,v .and means` forming radial105 section, and means separating the rotors havi

